1. Field of the Invention
This invention relates to the experimental stress analysis and more particularly to the optically assisted processing of photoelastic data.
2. Description of the Prior Art
In my previous invention U.S. Pat. No. 4,008,960 "Photoelastic Strain Gauge Coating and Method of Using Same" a standard photoelastic coating has been disclosed as a coating of standard shape and of standard boundary conditions (load-free boundary). The more detailed analysis of computations involved to separate strains, shows that the substantial computer time expenditures are inherent in the proposed technique. The bulk of these relates to the numerical convolution of certain functions obtained from the experiment. It is also shown in the papers: "Strain Separation in S.P.C.", Paper No. R79-160 and "Inversion Problem in Infinite S.P.C.", Paper No. R79-161 SESA Spring Meeting, 1979 by Z. Reytblatt that for the "infinite" coatings (that is the coatings whose bonded area is small compared to the total area) the averaged strains and the strains in the prototype-coating interface are certain convolutions.
The patent application "Polariscope and Filter Thereof" Ser. No. 038,575 discloses a method of obtaining images containing information on both principal stress difference and principal strain directions throughout the entire field of observation using filters containing a multiplicity of elements transmitting light of specified wavelengths and polarization planes. Semitransparent mirror films built in the slab of photoelastic materials, in general, are well known. However, the dichroic film application as a built-in film in photoelasticity has not been disclosed.
Devices capable of producing the Fourier transforms of given functions, their inverses and/or convolutions are well known (U.S. Pat. No. 3,544,197 "Optical Cross correlation", as an example).